1. Field of the Invention
The present invention relates to an assembly and process for drilling multiple subterranean wells from a single or common well bore and for completing such wells via separate casings positioned within the common well bore, and more particularly, to such assembly and process for drilling and completing multiple subterranean wells from a single or common well bore which will permit such wells to be separated at or near the surface of the earth during and after drilling and completion.
2. Description of Related Art:
Increasingly, well bores are being drilled into subterranean formations at an orientation which is purposely deviated from true vertical by means of conventional whipstock technology or a mud motor secured in the drill string adjacent the drill bit. In fractured subterranean formations, deviated wells are utilized to increase the area of drainage defined by the well within the subterranean formation, and thus, increase production of hydrocarbons from the subterranean formation. An inherent problem in utilizing a conventional whipstock to drill a deviated well is that both the depth and radial orientation of the whipstock is set when the whipstock is positioned in the well bore and cannot be changed without retrieving the whipstock from the well bore and changing the depth and/or radial orientation thereof.
In addition, wells drilled from offshore drilling platforms are usually deviated to increase the number of wells which can be drilled and completed from a single platform. Offshore drilling platforms which are utilized in deep water to drill and complete wells in a subterranean formation vary in size, structure, and cost depending upon the water depth and the loads in which the platform will be set. For example, a platform may be constructed to be supported in part by one leg or caisson which extends to the ocean floor or by as many as eight such legs or caissons. Costs of such offshore drilling platforms vary from approximately $5,000,000 to $500,000,000. Each offshore drilling platform is equipped with a set number of slots via which deviated wells can be drilled and completed through casings which are secured to the platform by conventional techniques.
Thus, a need exists for an assembly and processes for drilling and completing multiple cased wells from a single or common well bore so as to reduce capital expenditures for onshore and offshore wells.
Accordingly, it is an object of the present invention to provide an assembly and a process for drilling and completing multiple wells within subterranean formation(s) from a single or common well bore wherein such multiple wells are separated during and after drilling and completion at or adjacent to the surface of the earth.
It is another object of the present invention to provide an assembly and a process for drilling and completing multiple wells within subterranean formation(s) from a single or common well bore without using moveable downhole components.
It is a further object of the present invention to complete such multiple, cased wells in a manner such that remedial operations can be conducted on one well while hydrocarbons from the subterranean formation are simultaneously being produced from or fluid is being injected into such formation by means of the other well(s) which are completed via separate casings.
It is a still further object of the present invention to provide such an assembly and process for drilling multiple cased wells from a single or common well bore which is relatively simple in construction, which permits production casing of each multiple well to separately depend from the surface apparatus, and which provides that the separate production casing of each multiple well extend from the subterranean formation of interest to the surface.